Materials which contain starch and protein, often accompanied by other soluble and insoluble substances, are commercially processed to separate these materials into various fractions, which may also be further processed, if desired. The weight of each fraction, its composition and the total percentage of material recovered depends both upon the composition of the raw material and on the exact processing steps to which it is subjected.
In commercial processing, it is desired to maximize the total value of all the fractions recovered, as long as the increased value is greater than any increased costs of processing. In general, the value of a fraction is greater as its purity is increased, and the total value is greater with increased recovery of the more valuable fractions.
The art to which this invention relates has been very active through the years, as evidenced by the following patents:
U.S. Pat. No. 2,698,826 refers to a process wherein a starchy material is transformed into a magma containing solubles and unconverted starch which is centrifuged to provide an overflow containing the solubles and an underflow containing the starch. A fresh water wash is introduced into the centrifuge zone.
In U.S. Pat. No. 3,236,740 there is disclosed a process for producing alcohol which entails degerminating corn to form a germ fraction and a degerminated starchy fraction; extracting the germ fraction for its germ oil; adding some of the extract to the degerminated fraction; cooking the combined fractions; neutralizing the cooked material, cooling the cooked mash to saccharifying temperature; saccharifying the cooled mash cooling to fermenting temperature; fermenting and recovering the alcohol.
U.S. Pat. No. 3,236,740 discloses a process wherein, instead of milling the fiber after germ removal and separation of the "grit starch", the fiber and its associated starch and protein are put through an alcohol-making procedure. In this process, yeast is not recycled and starch is lost to fermentation with the germ and gluten coming from the primary separator.
U.S. Pat. Nos. 2,230,318 and 2,063,223 describe the re-use of yeast to increase alcohol yeilds but only in reference to molasses, which is clarified before fermentation.
Distilleries typically produce grain alcohol by converting the starch in grain to sugar, fermenting the sugar to alcohol, recovering the alcohol by distillation, and recovering the remaining materials by removing the water. This residual material is sold as animal feed and has much less value than the alcohol. The total value of production is increased by maximizing the recovery of starch as alcohol rather than allowing it to go to the feed fraction which has lower value. Furthermore, the value of the feed is improved through effective increase of its protein content when the starch is kept out of it.
Accordingly, it is an object of the present invention to provide a process for producing alcohol from corn, starchy roots, legumes and grain which yields a higher percentage of alcohol than prior art processes.
Another object of the present invention is to provide a process for producing by-products with a much higher economic value than prior art processes.
A further object of the present invention is to provide a process for producing alcohol which uses less water and energy than prior known processes.
Still another object of the present invention is to produce a new and valuable product, destarched corn gluten.